#include<stdio.h>
int main()
{
  int arr[] = {1,2,3,4,5,6,7,8,9,10};
  int left = 0;
  int right = sizeof(arr)/sizeof(arr[0])-1;
  int key = 7;
  int mid = 0;
  while(left<=right)
  {
   mid = (left+right)/2;
   if(arr[mid]>key)
   {
    right = mid-1;
   }
   else if(arr[mid] < key)
   {
    left = mid+1;
   }
   else
   break;
  }
  if(left <= right)
  printf("找到了,下标是%d\n", mid);
  else
  printf("找不到\n");
 return 0;
 }